Firearm drive spring device



Sept 7, 1965 H. P. swlEsKowsKl 3,204,531

FIREARM DRIVE SPRING DEVICE Filed March 4. 1964 [WMM/Mm a ATTORN EY United States Patent O 3,204,531 FIREARM DRIVE SPRING DEVICE Henry P. Swieskowski, Springfield, Mass., assigner to the United States of America as represented by the Secretary of the Army Filed Mar. 4, 1964, Ser. No. 349,508 3 Claims. (Cl. 89-199) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

v This invention relates to automatic firearms and pertains particularly to the drive spring devices for driving a reciprocating bolt to battery position.

In the design of some automatic firearms with a reciprocating bolt, it is necessary to provide the bolt with a long stroke and to have it held with considerable force by the drive spring in battery position. With such designs, a problem arises respective to the drive spring because, with the severe space limitation in guns and the required preload in the spring, the limited length of the drive spring causes the stresses therein to come close to maximum limits when the bolt is in recoil position and the drive spring is at the minimum operating height. Consequently, a slight variation in the stresses in the spring over the maximum limits will cause the drive spring to take a set and thereby adversely affect the operation of the firearm. Moreover, because of the excessive stresses therein, the life of the spring is considerably reduced.

It is, therefore, the object of this invention to provide a drive spring device having an auxiliary drive spring which assists the main drive spring in providing the required force against the bolt when in battery position, so that the preload of the main drive spring can be proportionately reduced, and means for making the auxiliary drive spring active against the bolt only when the bolt is adjacent battery position.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from' a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a fragmentary view of a iirearm shown in longitudinal section and shows the firearm bolt in battery position;

FIG. 2 is a view similar to FIG. 1 but shows the auxiliary spring disconnected from the bolt assembly during the recoil stroke thereof;

FIG. 3 is a view similar to FIGS. 1 and 2 but shows the auxiliary spring freed for reengagement with the bolt assembly during counterrecoil stroke of the bolt assembly; and

FIG. 4 is a view taken along line 4 4 of FIG. 2 with the shuttle assembly shown in full.

Shown in the figures is a firearm 12 such as is disclosed by John L. Lochhead in his patent application, Serial No. 354,183 filed March 23, 1964 entitled Cartridge Feeding Mechanism for Fixed-Barrel, Slide-Operated Guns. Firearm 12 includes a receiver 14 in which a two-piece bolt assembly 16 is mounted for reciprocation between a battery and a recoil position. Bolt assembly 16 includes a bolt 18 with a depending liange 20 and a slide 22 which is mounted for limited and relative longitudinal movement respective to the bolt for performing the operations of locking and unlocking the bolt at the battery position and which is provided with a depending tail section 24.

Bolt assembly 16 is returned to battery position by a drive spring device 26 after being driven to recoil position by discharge forces through drive means (not shown). Drive spring device 26 includes a guide tube 28, a drive spring 30 which is coiled around the outside of the guide ice tube, and an auxiliary spring 32 coiled within the tube. Drive spring device 26 is longitudinally disposed in receiver 14 parallel to the path of movement of bolt assembly 16 With the rear end supported by a back plate 34 for the receiver. An aperture 36 through iiange 20 receives drive spring device 2 6to permit uninterrupted displacement of bolt 18 relative thereto and a hole 38 having approximately the same diameter as the outside diameter of guide tube 28 is provided in tail section 24 to slidingly receive the guide tube, whereby the front end of drive spring 30 has contact with such tail section to act thereagainst. Drive spring 30 i's designed to have a preload less than that required in the irearm design when bolt assembly 16 is in battery position.

Slidingly mounted in guide tube 28 forwardly of auxiliary spring 32 is a shuttle 40 having a rectangular, vertically disposed channel 42 therein for receiving a pawl 44. Pawl 44 is mounted for pivotal displacement between a retracted position and an extended latching position by means of a pin 46 which extends transversely through shuttle 40 and the rear end of the pawl so that a top surface 48 of the pawl inclines upwardly and forwardly, when the pawl is in the latching position, and, when in such position, a front end 50 of the pawl is elevated above the periphery of shuttle 40. Pawl 44 is biased upwardly to the latching position by a spring 52.

A well 54 extends downwardly into shuttle 40 rearwardly of channel 42 and Slidingly mounted in such well is a detent 56 which is biased upwardly from a retracted to an engaging position by a spring 57. Well 54 and detent 56 are both of oval configuration in lateral crosssection, as shown in FIG. 4, to prevent rotation of the detent. The top of detent 56 contacts the inside wall of guide tube 28 to prevent the upward displacement of the detent past the engaging position. A lug 58 extends upwardly from the top of detent 56 and such lug is provided with a front cam surface 60 which extends downwardly and forwardly from the front end of a rear" cam surface 62 which extends upwardly and forwardly from the rear end of the lug.

Extending rearwardly into guide tube 28 from the front end thereof is a slot 64 which is arranged to Slidingly receive pawl 44 and which is terminated by a rear end 66. Spaced rearwardly in guide tube 28 from rear end 66 is an orifice 68 through which lug 58 extends when detent 56 is in the engaging position and which lug is provided with a vertical rear wall 70 and a front wall 72 that is chamfered to incline downwardly and forwardly to the inside wall of the guide tube. When detent 56 is in engaging position, front cam surface 60 and rear cam surface 62 are both located outside of guide tube 28.

Extending forwardly into slide 22 from the rear end of hole 38 is a triangular recess 74 which is arranged to receive the projecting portion of pawl 44 when in the latching position and which forms a cam slide 76 that inclines upwardly and forwardly from the rear end of the recess to a terminal wall 78. Terminal wall 78 is contactable by front end 50 of pawl 44 for transferring the energy in auxiliary spring 32 to slide 22, when the pawl is in the latching position, for biasing bolt assembly 16 to battery position. When bolt assembly 16 is in battery position,lauxiliary spring 32 has a preload which, together with the preload in drive spring 30, equals the required design load against the bolt assembly when in battery position.

Operation When bolt assembly 16 is in battery position, pawl 44 is in the latching position with front end 50 pressed against terminal wall 78 so that the energy in auxiliary spring 32 is transferred to slide 22 to assist drive spring 30 in holding bolt assembly 16 in battery position, and detent S6 is held retracted by contact of lug 58 with the inside of guide tube 28,-as shown in FIG. -1.

When firearm 12 is fired and bolt assembly 16 is energized for rearward displacement to recoil position, the recoil forces overcome the combined preloads of drive spring 30 and auxiliary spring 32, moving the bolt assembly rearwardly. As bolt assembly 16 moves rearwardly, rear end 66 of slot 64 comes into contact with the inclined top surface 48 of pawl 44 causing the pawl to be cammed downwardly out of recess 74, as best shown in FIG. 2, to disconnect front end 50 from terminal wall 78 and thereby free the bolt assembly from auxiliary spring 32 for continued rearward travel. Shuttle 40 is releasably held at its released position by the engagement of lug 58 with orifice 68.

When bolt assembly 16 returns to battery position, the rear end of cam slide 76 contacts rear cam surface 62 initiating displacement of lug 58 from oriiice 68. Final displacement of lug 58 to its retracted position is provided by the pressure of front cam surface 60 against front wall 72. With detent 56 disengaged from orifice 68, shuttle 40 is freed for forward displacement in guide tube 28 by auxiliary spring 32. As shuttle 40 moves forwardly and pawl 44 comes into increasing registry with slot 64, the pawl projects upwardly into recess 74 under the bias of spring 52 so that front end 50 contacts terminal wall 78 and thereby adds the energy of auxiliary spring 32 to that of drive spring 30 as bolt assembly 16 goes into battery position. j

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. In a rearm, a bolt assembly disposed for reciprocation between a battery and a recoil position, and a drive spring device for biasing said bolt assembly to the battery position and for applying a required design load against said bolt assembly when in battery position, said drive spring device including a drive spring acting against said bolt assembly during the entire stroke thereof between the recoil and battery positions and having a preload less than the required design load, an auxiliary spring having a preload equal to at least the difference between the required design load and the preload of said drive spring, and means for activating said auxiliary spring against said bolt assembly only when said bolt assembly is adjacent battery position.

2. The firearm as defined in claim 1 wherein said drive spring also includes a guide tube for receiving said auxiliary spring and said drive spring is coiled around the outside of said guide tube with one end acting against said bolt assembly, and wherein said means include a shuttle slidingly disposed in said guide tube and in contact with the front end of said auxiliary spring so as to be forward biased thereby, a pawl mounted on said shuttle for releasable Contact with said bolt assembly for transferring the forward bias of said auxiliary spring to said bolt assembly, cooperating means on said pawl and in said guide tube for disconnecting said pawl from said bolt assembly during commencement of the displacement thereof from battery position and to reconnect said pawl to said bolt assembly when adjacent said battery position.

3. The rearm as defined in claim 2 wherein said drive spring device also includes a detent having cooperation with an orifice in said guide tube for releasably holding said shuttle against displacement when said pawl is disconnected from said bolt assembly and to release said shuttle for transferring the bias of said auxiliary spring to said bolt assembly when adjacent battery position.

References Cited by the Examiner UNITED STATES PATENTS 2,659,994 11/53 Yale 89-199` 2,807,113 9/57 Ivy 89-199 BENJAMIN A. BORCHELT, Primary Examiner.

FRED C. MATTERN, IR., Examiner. 

1. IN A FIREARM, A BOLT ASSEMBLY DISPOSED FOR RECIPROCATION BETWEEN A BATTERY AND A RECOIL POSITION, AND A DRIVE SPRING DEVICE FOR BIASING SAID BOLT ASSEMBLY TO THE BATTERY POSITION AND FOR APPLYING A REQUIRRED DESIGN LOAD AGAINST SAID BOLT ASSEMBLY WHEN IN BATTERY POSITION, SAID DRIVE SPRING DEVICE INCLUDING A DRIVE SPRING ACTING AGAINST SAID BOLT ASSEMBLY DURING THE ENTIRE STROKE THEREOF BETWEEN THE RECOIL AND BATTERY POSITIONS AND HAVING A PRELOAD LESS THAN THE REQUIRED DESIGN LOAD, AN AUXILIARY SPRING HAVING A PRELOAD EQUAL TO AT LEAST THE DIFFERENCE BETWEEN THE REQUIRED DESIGN LOAD AND THE PRELOAD OF SAID DRIVE SPRING, AND MEANS FOR ACTIVATING SAID AUXILIARY SPRING AGAINST SAID BOLT ASSEMBLY ONLY WHEN SAID BOLT ASSEMBLY IS ADJACENT BATTERY POSITIN. 